As to my theory about the Sasquatch having a basis in reality, it goes something like this.
John Burns, the earliest chronicler and publicist of the Sasquatch (He's the one who coined the name), evidently regarded them as definitely human. Some of his reports, as I have previously mentioned, referred to the Sasquatch as conversing with the local Indians in their native dialects. There is one story of a Sasquatch fathering a child with an Indian woman he had kidnapped. When the town of Harrison in British Columbia proposed a Sasquatch hunt as part of an anniversary celebration in 1957, Burns protested vehemently, saying that they were people and deserved to be left alone.
There seems to be increasing evidence that other humans had settled in the New World prior to the Paleo-Indian migration. Let us suppose that these Sasquatch represented survivals of this pre-Indian settlement. They may have been taller on the average than the Indians of the region. According to some sources, anyone well over six feet is a "giant" to the B.C. Indians. Thus the Sasquatch could be well within human norms and still considered "giants." Mongoloids and their Amerindian counterparts have the least body hair, I believe, of any major human groups. The famous Kennewick Man, the best preserved example of a pre-paleo-Indian, is thought to have closest ethnic affinities to the Ainu people of Japan, known as the "Hairy Ainu." Thus, I think it is entirely possible that the real Sasquatch could be (or have been) modern humans. Hence, their physical remains would have attracted comparatively little attention from archaeologists.
Enter William Roe. At the time of "Sasquatch hunt" controversy, he turns up with a sworn affidavit in which he claimed to have seen a strange creature on Mica Mountain a few years earlier. A little later, his daughter made a drawing of the creature, which is sort of a bipedal gorilla with prominent hairy breasts.
Almost entirely based upon Roe's story, John Green, another BC journalist who had succeeded to Burns' mantle as the chronicler of the Sasquatch, concluded that they were apes, not humans, and identical to the Bigfoot reports coming out of California.
And so, the biped gorilla, an improbable, if not impossible, melange of ape from the waist up, human from the waist down, became the definitive type for the Bigfoot/Sasquatch and has remained so to this day.
I know there are others who have advanced the theory that the "human" Sasquatch of BC are (or were) for real and the ape-ish Bigfoot is a myth. I am inclining to think there may be something to this.